Photoconductive copolymers of styrene and acrolein derivatized with aryl amines



United States Patent PHGTGCUNDUCTIVE CGPOLYMERS 0F TYRENE ACROLEINDEPJVATEZED WiTH ARYL AMENES Siegfried Aftergut, Schenectady, N .Y.,assignor to General Electric Company, a corporation of New York NoDrawing. Filed Oct. 8, 1964, Ser. No. 402,635 8 'Clairns. (CL-Ztl-SZ)ABSTRACT OF THE DES CLOSURE A copolymerized styrene-acrolein resin isreacted with an aromatic amine or hydrazine to give a photoconductivematerial.

This invention relates to organic photoconductive materials useful inapplications requiring photoconductors such as photoplastic recording.More particularly, this invention relates to photoconductive materialscomprising a polyal-dehyde resin modified by the addition of aromaticamines or hydrazines.

The recording of information on a deformable photoconductive medium inthe form of minute light-modifying deformations is known. By one suchmethod of information storage, the deformations are formed on thestorage medium by first charging the surface to a uniform potential,then exposing to electromagnetic radiation and finally making the effectof the radiation visible by heatsoftening the deformable storage medium.Exposure to electromagnetic radiation produces a latent electrostaticimage. On softening the storage medium, the electrostatic forces causethe formation of physical deformations which correspond to the chargepattern of the latent image. Upon cooling the medium, the deformationsbecome permanently fixed on the surface of the recording medium and arethereby permanently stored unless erased by reheating. The informationstored in the form of these deformations is retrieved by projecting abeam of light through the medium. The projecting light is diffracted orrefracted by the deformations to produce a spatial light imagecorresponding to the original image.

The information storage medium as known may comprise a multilayerlaminate, one of the layers comprising a photoconductive material. Thelaminate may be prepared in the form of any suitable configuration suchas, for example, a tape, disc, or sheet. The recording layer of thelaminate may be prepared from a solid thermoplastic polymer or a mixtureof such polymers Which are deformable by the application of heat.

Organic photoconductors usually do not have desirable mechanical andfilm-forming properties; hence, it is the general practice to dissolveor disperse these photoconductors in an inert polymeric media such aspolystyrene and polyvinyl chloride. The mixtures of inert media andphotoconductors have considerable drawbacks in practical applicationsincluding lack of homogeneity, because of the incompatibility of thecomponents, and difliculty of preparing thin films due to the solubilitydifierences of the components. Further, there maybe a decrease ofphotoconductor concentration during storage or use due to photoconductorvolatility. These disadvantages are eliminated by the use ofphotoconductor compositions made in accordance with my invention. Suchphotoconductors are characterized by their homogeneity, stability, andfilmforming ability.

It is, therefore, one object of my invention to provide a stablephotoconductive material.

It is a further object of my invention to provide a homogeneousphotoconductive material.

It is a further object of my invention to provide a ice photoconductivematerial that has excellent film-forming properties.

Briefly, this invention relates to the chemical tion of a copolymerizedstyrene-acrolein resin, common- 5 ly known as a polyaldehyde, byco-reacting the resin with aromatic amines or hydrazines to give aphotoconductive material having unexpected properties.

Those parts of my invention which are considered to be new are set forthin detail in the claims appended hereto. The invention, however, may bebetter understood and further objects and advantages thereof appreciatedfrom a consideration of the following description.

The polyaldehyde resins are known in the art. While others may be used,the polyaldehyde resin used in the examples given in this applicationcomprise a photoelectrically inert copolymer of styrene and acrolelnhaving the following formula:

modifica- Formula I I:CH2(IJHEGH2CH I (1H H 0 at The properties of thestyrene-acrolein copolymer are listed as follows:

Elemental analysis of the material gave 83.7% carbon and 8.3% hydrogen,leaving 8.0% for oxygen by difference. According to this analysis,values for it and m are about 1.5 and 1, respectively, so that the resincontains 0.47 equivalent of carbonyl per 100 g.

In carrying out my invention the copolymer above referred to was allowedto react with a number of aromatic amines and hydrazines. The reactiontook place between the carbonyl group of the resin and amino group ofthe co-reactant to give Schitf base linkages With the amines and thehydrazones with the hydrazines.

Formula II below is illustrative of a structure when the reacting amineis N,N-dimethyl-p-phenylenediamine. If less than a stoichiometric amountof amine is used or if the reaction is incomplete the resulting productwould contain some unreacted acrolein residues.

Formula II CHzCIJH CHMCH H CH3 Formula III oHlon oHloH n N- O2 Jn N02111 As previously stated, the polyaldehyde resin is reacted witharomatic amines and hydrazines. The amino derivatives correspond to thegeneral formula lTIHa where R is hydrogen, alkyl, alkoxy, alkylamine,nitro, phenylazo, hydroxy, acyl, aldehydo, halogen, cyano, phenylamino,heterocyclic residue and 2,4-dinitrophenylamino and R" may be any ofthese substituents or identical to R.

V The polyaldehyde resin may also be co-reacted with hydrazinederivatives which correspond to the general formula NHNH2 R! where R ishydrogen, alkyl, alkoxy, akylarnine, nitro, phenylazo, hydroxy, acyl,aldehydo, halogen, eyano, phenylamino, heterocyclic residue, 2,4dinitrophenylamino and R may be any of these substituents or identicalto R.

The following specific examples are given to illustrate the variousadvantages of the present invention and are not to be taken as limitingin any way. All parts are by weight.

Example 1 A mixture consisting of 7.5 g. of copolymer of styrene andacrolein, 4 g. of N,N-dimethyl-p-phenylenediamine, and 50 ml. of toluenewas heated at reflux for 5 hours. The solution was cooled and addeddropwise with stirring to 400 ml. of methanol to give 8 g. of atan-colored precipitate of a copolymer of styrene and acroleinderivatized with N,N-dimethyl-p-phenylenediamine. The melting point ofthe product was 168-170 C. The analysis was: 84.2% C, 8.5% H, and 7.1%N. Since the percentage of these elements adds to 99.8%, it is inferredthat essentially all the carbonyl groups originally present have beenconverted.

Example 2 melting range of 178195 C. The analysis was 66.6% C,

5.6% H, and 12.9% N. The percentage of oxygen was 14.9 by difference.Since the ratio of nitrogen to oxygen atoms in the product can be shownto be one, it is inferred that all the carbonyl groups in the startingmaterial were derivatized.

Example 3 Using the general method described in Example 1, there wasprepared a copolymer of styrene and acrolein derivatized withp-phenylazoaniline, having a melting point of l63-164 C. and containing83.0% C, 7.5% H, and 4.8% N. 1

Example 4 By the general method described in Example 2 there wasprepared a copolymer of styrene and acrolein derivatized withp-nitroaniline having a melting point of 4 187-192" C. and having ananalysis of 77.3% C, 7.1% H, and 5.8% N.

Example 5 By the general method of Example 2 there was prepared acopolymer of styrene and acrolein derivatized with2,4-dinitro-4'-aminodiphenylamine having a melting point of 158-170 C.and having an analysis of 74.2% C, 6.3% H, and 8.7% N.

Example 6 Using the general method described in Example 2 there wasprepared a copolymer of styrene and acrolein derivatized with4-methoxy-2-nitroaniline having an analysis of 82.7% C, 8.3% H, and0.59% N.

A typical application of the above composition is as follows. A benzenesolution was prepared comprising 20% of the copolymer of styrene andacrolein derivatized with p-phenylazoaniline of melting point of 160-165C., 55% of polystyrene, and 25% of a polystyrene plasticizer. Thesolution was used for casting a thin film on a glass slide coated with athin, electrically-conducting layer of tin oxide. The polymeric film wasgiven an electrostatic charge in the dark by means of corona discharge.An ultra-violet image was projected into the charged film layer and thefilm was quickly heated to the flow point. There was obtained an imageon the film in the form of ripplesor grooves which corresponded to theprojected image. The ripples could be removed and the film restored toits original conditions by re-melting the polymeric film.

As many widely different embodiments of this invention may be madewithout departing from the spirit and scope thereof, it is to beunderstood that this invention is not limited to the specificembodiments thereof except as defined in the appended claims.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. A photoconductive thermoplastic material consisting essentially ofthe reaction product of a styrene-acrolein resin and a compound havingthe formula R! where R is hydrogen, alkyl, alkoxy, alkylamine, nitro,phenylazo, hydroxy, acyl, aldehydo, halogen, cyano, phenylamino,heterocyclic residue, 2,4-dinitrophenylamino, and R" is selected fromthe same group as R.

2. A photoconductive thermoplastic material consisting essentially ofthe reaction product of a styrene-acrolein resin andN,-N-dirnethylparaphenylenediamine.

3. A photoconductive thermoplastic material consisting essentially ofthe reaction product of a styrene-acrolein resin andparaphenylazoaniline.

4. A photoconductive thermoplastic material consisting essentially ofthe reaction product of a styrene-acrolein resin and paranitroaniline.

5. A photoconductive thermoplastic material consisting essentially ofthe reaction product of a styrene-acrolein resin and2,4-dinitro-4'-aminodiphenylamine.

6. A photoconductive thermoplastic material consisting essentially ofthe reaction product of a styrene-acrolein resin and2-methoxy-2-nitroaniline.

7. A photoconductive thermoplastic material consisting essentially ofthe reaction product of a styrene-acrolein resin and a compound havingthe formula ITIHNH:

3,373,141 5 6 Where R is hydrogen, alkyl, alkoxy, alkylamine, nitro,References Cited phenylazo, hydroxy, acyl, aldehydo, halogen, cyano,UNITED STATES PATENTS phenylamino, heterocyclic residue,2,4-dinitrophenylamino, and R" is selected from the same group as R.3,163,531 12/1964 Schlesmger 250.725

8. A photoconductive thermoplastic material consisting 5 essentially ofthe reaction product of a styrene-acrolein WILLIAM SHORT Prlma'yExammer' resin and 2,4dinitrophenylhydrazine. E. M. WOODBERRY, AssistantExaminer.

